Method and apparatus for laying pipelines

Abstract

Method and apparatus for laying pipelines wherein a number of operating trolleys running on the bottom of an excavation are powered from service vehicles running on a service path to the side of the excavation to enable said operating trolleys to position and connect additional pipeline lengths before advancing to deposit the completed pipeline on the excavation bottom.

I claim: 
     
       1. A method of laying large diameter pipelines, especially oil pipelines of, for example, one to two meters in diameter, comprising the steps of: preparing an elongated excavation to receive a pipeline along the axis thereof;   supporting the end of an already completed length of pipeline on at least one operating trolley movable along the bottom of the excavation in which the pipeline is being laid;   lowering an additional length of pipeline into the excavation on to at least one further operating trolley movable along the excavation bottom ahead of the already completed pipeline;   positioning the end of the additional pipeline length in juxtaposition with the end of the already completed pipeline by use of the operating trolleys and utilizing welding equipment carried by the operating trolleys to weld the additional pipeline length to the already completed pipeline while the pipelines are in the excavation;   supplying power to the operating trolleys for movement thereof and for operating the welding equipment thereon from service vehicles movable along a service path outside of and to the side of the excavation; and   advancing the operating trolleys along the bottom of the excavation after connection of the additional pipeline length has been completed, so that said at least one operating trolley lays a further portion of completed pipeline on to the bottom of the excavation and said at least one further operating trolley is advanced ahead of the completed pipeline ready to receive a further pipeline length to be connected and laid on the bottom of the excavation.   
     
     
       2. A method according to claim 1, comprising positioning the operating trolleys in sequence to perform the following operations in succession: welding the additional pipe length;   checking the welded seam;   sheathing an additional connected length of pipeline; and   laying the completed pipeline on to the excavation bottom.   
     
     
       3. A method according to claim 1, comprising carrying the additional pipeline length and lowering said pipeline length into the excavation by means of a service vehicle located outside of the excavation. 
     
     
       4. A method according to claim 1, comprising chamfering the ends of the additional pipeline length prior to connection to the already completed pipeline, the chamfering operation being carried out during transport of the additional pipeline length to the excavation. 
     
     
       5. A method according to claim 1, comprising scavenging and cleaning the excavation prior to the operation of laying the pipeline on to the excavation bottom, the scavenging and cleaning operations being carried out by the last operating trolley. 
     
     
       6. Apparatus for laying pipelines in an excavation, especially large diameter oil pipelines of, for example, one to two meters in diameter, comprising: a plurality of operating trolley located inside the excavation, each trolley including: a tracked chassis for running on the bottom of an excavation in which the pipeline is being laid;   hydraulic motors in the chassis for driving the chassis track;   power equipment on the chassis for performing operations on the pipeline being laid, at least one of said trolleys carrying welding equipment for welding sections of pipeline together;     means on the chassis for adjustably supporting a length of pipeline; and   an hydraulic fluid supply line leading from the chassis to enable the motors, power equipment and adjustable supporting means to be supplied with power; and   at least one service vehicle outside the excavation and to the side of the excavation coupled to the hydraulic fluid supply line of at least two of said trolleys for supplying power fluid to said at least two trolleys.   
     
     
       7. Apparatus according to claim 6, wherein the adjustable supporting means of said trolleys include rollers arranged in pairs to form a saddle for the pipeline length, each roller being supported by a stem mounted on the piston of an hydraulic jack that is operable to control tilting of the pipeline length. 
     
     
       8. Apparatus according to claim 6, wherein the power equipment includes at least two electrowelding sets. 
     
     
       9. Apparatus according to claim 6, wherein the power equipment on said trolleys includes means controlled by hydraulic fluid for providing the pipeline with a protective sheath. 
     
     
       10. Apparatus according to claim 6, wherein the power equipment on at least one of said trolleys includes testing means for testing the welded seams made in the pipeline. 
     
     
       11. Apparatus according to claim 6, wherein the power equipment on at least one of said trolleys includes means for scavenging the excavation before laying the pipeline on the excavation bottom.